This invention relates to an automatic energy supply system of the multi-rate calculating type utilized by such public energy supply utilities as electric power, town gas and aqueduct water supply companies.
According to prior art rate collecting methods a meter inspector inspects integrating demand meters installed in the customer houses, then debit notes for respective customers are prepared by computing the result of inspection of the demand meters by means of an electronic computer. The debit notes are then sent to the customers to collect the rates through banks or service men who visit the customers.
Such method of collecting rates requires a large member of service men so that it is not suitable in sparsely populated areas. Collection of the rates through banks adds extra cost. Accordingly, it is necessary to develop a novel system of inspecting the demand meters and collecting the rates.
As an approach to this problem, an automatic energy supply systems have been developed for vending such public energy as electric power, town gas and aqueduct water. According to one system the customer buys a chip with which he can consume electric power of 100 KWH, for example, and inserts this chip into an automatic electricity supply device installed in his house for consuming electric power corresponding to the price of the chip. By periodically inserting the chips into the automatic electricity supply device continuous supply of power is ensured without interruption. With this system since it is possible to supply public energy in an amount already bought by the customer, troublesome jobs of meter inspection, preparation of debit notes and collection of the rates are eliminated. Examples of this system are disclosed in U.S. Pat. Nos. 3,783,988 and 3,778,637, for example.
With such prior art energy supply system, however, in the case of electricity, for example, as the quantity of electricity is determined by the inserted chip, such system is not applicable unless the rate of electric power is constant. The present date rate is extremely complicated and differs greatly not only for different power companies but also for different types of use. Even when the rate is determined according to the reading of a watthour meter, the rate is different for respective customers due to the difference in the base rate, multi-stage increasing or decreasing rate, a tax exemption limit, etc. For this reason, the rate may be different even for the same amount of electricity. Accordingly, when a conventional watthour meter is used for the present rate system, records of the amount of the used electric power in unit calculation interval, usually one month, are kept, and these records are collected at the time of the periodical inspection (once in year). Thereafter, the total amount of the power used, base rate, multi-stage rate and the tax exemption limit, etc., are calculated. However, as such calculation involves complicated calculation, the advantage of decreasing the number of meter inspections decreases greatly. For this reason, such system is practical only in extremely sparsely populated or extremely densely populated areas where the business of meter reading and rate collection is too expensive. Accordingly, the application of the chip system is limited, especially in the present day multi-rate system.